Tropical Storm MAWAR Advisory Sun Jul 01

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (FOUR) WARNING
NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 04W, LOCATED APPROXIMATELY 350 NM EAST
OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER
THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES A
CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED
CONVECTIVE BANDING WRAPPING INTO DEFINED LLCC. CONSEQUENTLY, THE
31/18Z DVORAK INTENSITY ESTIMATES HAVE INCREASED TO T1.5 (25 KNOTS)
AND LIMITED SURFACE OBSERVATIONS HAVE INDICATED DECREASING SLP TO
NEAR 1004 MB, SUPPORTING THE CURRENT INTENSITY ASSESSMENT OF 25
KNOTS. RECENT MICROWAVE IMAGERY HAS BEEN SPARSE, HOWEVER, A 311906Z
PARTIAL AMSU IMAGE OVER THE WESTERN SEMI-CIRCLE SUPPORTS THE CURRENT
POSITION WITH FAIR CONFIDENCE AND SHOWS IMPROVED DEEP CONVECTIVE
BANDING AND IMPROVED ORGANIZATION. UPPER-LEVEL ANALYSIS INDICATES A
FAVORABLE ENVIRONMENT CHARACTERIZED BY WEAK VERTICAL WIND SHEAR
(VWS) AND EXCELLENT, NEARLY RADIAL OUTFLOW ENHANCED BY A TUTT CELL
NEAR GUAM AND AN ANTICYCLONE IN THE SOUTHERN HEMISPHERE.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
   B. TD 04W IS CURRENTLY TRACKING ALONG THE SOUTHWEST PERIPHERY OF
THE LOW-LEVEL SUBTROPICAL RIDGE, WHICH EXTENDS WESTWARD TO TAIWAN
FROM A STRONG PERSISTENT HIGH NEAR 30N 170W. THE 31/12Z 500 MB
ANALYSIS INDICATES THAT THE DOMINANT STEERING INFLUENCE IS THE
EASTERN SUBTROPICAL RIDGE (STR). THIS ANALYSIS ALSO SHOWS THAT THE
WESTERN STR HAS RETROGRADED WESTWARD (WEST OF HONG KONG) DUE TO
PREVAILING WESTERLY FLOW EXTENDING OVER THE EAST CHINA SEA AND
TAIWAN. THIS SYNOPTIC PATTERN IS FORECAST TO REMAIN STATIC THROUGH
THE FORECAST PERIOD WITH A MIDLATITUDE SHORTWAVE TROUGH FORECAST TO
DEEPEN OVER THE EAST CHINA SEA NEAR TAU 72. THEREFORE, THERE IS HIGH
CONFIDENCE IN THE SHARP RE-CURVE SCENARIO WITH A LOW PROBABILITY OF
A TRACK INTO THE SOUTH CHINA SEA. AVAILABLE MODEL GUIDANCE IS IN
TIGHT AGREEMENT WITH THE EXCEPTION OF THE RE-CURVE AREA EAST OF
LUZON. THIS FORECAST IS POSITIONED WEST OF THE MODEL CONSENSUS
THROUGH TAU 72 FAVORING A MORE SUSTAINED NORTHWESTWARD TRACK PRIOR
TO RE-CURVATURE DUE TO THE POSITION OF THE STR TO THE NORTH AS
PREVIOUSLY DISCUSSED. TD 04W IS FORECAST TO INTENSIFY SLOWLY THROUGH
TAU 24 AS IT CONSOLIDATES BUT SHOULD QUICKLY STRENGTHEN TO A PEAK
INTENSITY OF 80 KNOTS BY TAU 72.
   C. IN THE EXTENDED PERIOD, TD 04W IS EXPECTED TO ROUND THE
NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE AND BEGIN TO
INTERACT WITH MIDLATITUDE WESTERLY FLOW. THEREFORE, THE SYSTEM WILL
BEGIN TO WEAKEN AND TRACK OVER COOLER SST (LESS THAN 25C) WHILE
BEGINNING EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 96. THE SYSTEM IS
EXPECTED TO COMPLETE ETT AFTER TAU 120 AS IT BECOMES EMBEDDED WITHIN
THE BAROCLINIC ZONE WELL SOUTH OF JAPAN AND ACCELERATES EASTWARD.
THERE IS HIGH CONFIDENCE IN THIS PORTION OF THE TRACK DUE TO THE
RELATIVELY ZONAL WESTERLY JET FORECAST BY ALL THE DYNAMIC MODELS TO
REMAIN ENTRENCHED OVER (AND WELL SOUTH OF) JAPAN. ADDITIONALLY, THE
SYSTEM SHOULD TRACK EAST OF OKINAWA BUT MAY PRODUCE INCREASED WINDS
AS THE EXTREME NORTHWESTERN PERIPHERY OF THE SYSTEM INTERACTS WITH A
DEVELOPING MIDLATITUDE HIGH.//
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